PROJECT[unreadable]SUMMARY[unreadable] [unreadable] If[unreadable]fertilized,[unreadable]all[unreadable]eggs[unreadable]undergo[unreadable]an[unreadable]egg?to?embryo[unreadable]transition.[unreadable]Within[unreadable]minutes[unreadable]or[unreadable] hours[unreadable]of[unreadable]insemination,[unreadable]depending[unreadable]on[unreadable]the[unreadable]animal,[unreadable]the[unreadable]egg[unreadable]shuffles[unreadable]its[unreadable]existing[unreadable]molecular[unreadable] machinery[unreadable]and[unreadable]transforms[unreadable]itself[unreadable]into[unreadable]a[unreadable]cell[unreadable]with[unreadable]vastly[unreadable]different[unreadable]developmental[unreadable]potential.[unreadable] The[unreadable]first[unreadable]mechanistic[unreadable]alteration[unreadable]of[unreadable]this[unreadable]egg?to?embryo[unreadable]transition[unreadable]establishes[unreadable]the[unreadable]block[unreadable]to[unreadable] polyspermy,[unreadable]which[unreadable]is[unreadable]followed[unreadable]by[unreadable]and[unreadable]integrated[unreadable]with[unreadable]the[unreadable]turnover[unreadable]of[unreadable]maternal[unreadable]mRNA[unreadable] and[unreadable]cytoplasmic[unreadable]proteins,[unreadable]altered[unreadable]signal[unreadable]transduction[unreadable]capabilities,[unreadable]and[unreadable]changes[unreadable]at[unreadable]the[unreadable]cell[unreadable] surface[unreadable]including[unreadable]addition[unreadable]and[unreadable]removal[unreadable]of[unreadable]specific[unreadable]membrane[unreadable]proteins[unreadable]and[unreadable]lipids.[unreadable]This[unreadable] transition[unreadable]is[unreadable]independent[unreadable]of[unreadable]new[unreadable]transcriptional[unreadable]activity,[unreadable]and[unreadable]for[unreadable]technical[unreadable]reasons,[unreadable]a[unreadable] majority[unreadable]of[unreadable]recent[unreadable]research[unreadable]towards[unreadable]understanding[unreadable]the[unreadable]egg?to?embryo[unreadable]transition[unreadable]has[unreadable] focused[unreadable]on[unreadable]signal[unreadable]transduction[unreadable]mechanisms[unreadable]and[unreadable]changes[unreadable]in[unreadable]mRNAs.[unreadable]The[unreadable]sea[unreadable]urchin[unreadable]and[unreadable] starfish,[unreadable]however,[unreadable]offer[unreadable]an[unreadable]opportunity[unreadable]to[unreadable]examine[unreadable]the[unreadable]changes[unreadable]that[unreadable]occur[unreadable]specifically[unreadable]at[unreadable] the[unreadable]cell[unreadable]surface.[unreadable]While[unreadable]the[unreadable]details[unreadable]of[unreadable]this[unreadable]process[unreadable]differ[unreadable]among[unreadable]animals,[unreadable]as[unreadable]with[unreadable]much[unreadable]of[unreadable] the[unreadable]reproductive[unreadable]phenomena,[unreadable]all[unreadable]eggs[unreadable]undergo[unreadable]this[unreadable]general[unreadable]transition.[unreadable]We[unreadable]will[unreadable]take[unreadable] advantage[unreadable]of[unreadable]the[unreadable]sea[unreadable]urchin[unreadable]and[unreadable]starfish[unreadable]because[unreadable]1)[unreadable]millions[unreadable]of[unreadable]oocytes,[unreadable]eggs[unreadable]and[unreadable] embryos[unreadable]are[unreadable]readily[unreadable]obtained;[unreadable]2)[unreadable]all[unreadable]the[unreadable]major[unreadable]proteins[unreadable]of[unreadable]the[unreadable]cortical[unreadable]granules[unreadable]have[unreadable]been[unreadable] defined;[unreadable]3)[unreadable]the[unreadable]egg[unreadable]and[unreadable]oocyte[unreadable]plasma[unreadable]membrane[unreadable]can[unreadable]be[unreadable]manipulated[unreadable]experimentally[unreadable]in[unreadable] many[unreadable]ways;[unreadable]and[unreadable]4)[unreadable]the[unreadable]genome[unreadable]sequence[unreadable]and[unreadable]genomic[unreadable]resources[unreadable]from[unreadable]the[unreadable]sea[unreadable]urchin[unreadable] Strongylocentrotus[unreadable]purpuratus[unreadable]are[unreadable]available.[unreadable]Results[unreadable]of[unreadable]this[unreadable]study[unreadable]will[unreadable]elucidate[unreadable]conserved[unreadable] mechanisms[unreadable]of[unreadable]this[unreadable]major[unreadable]developmental[unreadable]transition[unreadable]in[unreadable]all[unreadable]animals.[unreadable]Furthermore,[unreadable]because[unreadable] the[unreadable]changes[unreadable]examined[unreadable]here[unreadable]are[unreadable]at[unreadable]the[unreadable]cell[unreadable]surface,[unreadable]they[unreadable]will[unreadable]help[unreadable]clinicians[unreadable]develop[unreadable]new[unreadable] methods[unreadable]to[unreadable]non?invasively[unreadable]assess[unreadable]developmental[unreadable]potential[unreadable]in[unreadable]IVF[unreadable]applications[unreadable]for[unreadable] humans.[unreadable][unreadable] [unreadable] PROJECT[unreadable]NARRATIVE[unreadable] [unreadable] Immediately[unreadable]after[unreadable]fertilization,[unreadable]the[unreadable]egg[unreadable]rapidly[unreadable]transforms[unreadable]into[unreadable]an[unreadable]embryo[unreadable]with[unreadable] many[unreadable]new[unreadable]biochemical,[unreadable]cellular,[unreadable]and[unreadable]developmental[unreadable]features.[unreadable]This[unreadable]essential[unreadable]change[unreadable]is[unreadable] programmed[unreadable]into[unreadable]the[unreadable]egg[unreadable]and[unreadable]is[unreadable]independent[unreadable]of[unreadable]new[unreadable]gene[unreadable]expression;[unreadable]i.e.[unreadable]they[unreadable]reflect[unreadable] changes[unreadable]of[unreadable]the[unreadable]existing[unreadable]molecular[unreadable]machinery.[unreadable]Our[unreadable]research[unreadable]focuses[unreadable]on[unreadable]the[unreadable]changes[unreadable]that[unreadable] occur[unreadable]on[unreadable]the[unreadable]cell[unreadable]surface[unreadable]of[unreadable]the[unreadable]egg?to?embryo[unreadable]transition.[unreadable]These[unreadable]are[unreadable]some[unreadable]of[unreadable]the[unreadable]most[unreadable] rapid[unreadable]and[unreadable]conserved[unreadable]changes[unreadable]that[unreadable]occur[unreadable]in[unreadable]embryos[unreadable]and[unreadable]are[unreadable]detectable[unreadable]from[unreadable]the[unreadable]outside[unreadable] of[unreadable]the[unreadable]cell.[unreadable]Thus,[unreadable]this[unreadable]research[unreadable]will[unreadable]lead[unreadable]to[unreadable]a[unreadable]better[unreadable]understanding[unreadable]of[unreadable]a[unreadable]major[unreadable]transition[unreadable]in[unreadable] fertilization[unreadable]and[unreadable]development[unreadable]of[unreadable]all[unreadable]animals,[unreadable]and[unreadable]to[unreadable]the[unreadable]identification[unreadable]of[unreadable]non?invasive,[unreadable] early[unreadable]markers[unreadable]indicative[unreadable]of[unreadable]successful[unreadable]development.[unreadable]Our[unreadable]results[unreadable]will[unreadable]have[unreadable]particular[unreadable] significance[unreadable]to[unreadable]clinical[unreadable]IVF[unreadable]predictions[unreadable]in[unreadable]human[unreadable]reproductive[unreadable]health.[unreadable]